Various types of currency validators or acceptors have been known in the past. Typically, such acceptors are of one of two types. Slot acceptors generally provide means for receiving the bill or note in a slot, subsequently transporting the note past a test station into a receiving area once the bill has been authenticated. In contradistinction, tray acceptors are of the type in which the bill or currency is laid in a tray and the tray is then manually moved to a test position where the bill is retrieved from the tray if authenticated. The invention herein is particularly concerned with slot acceptors of the type wherein a magnetic head is used to read patterns on the paper, generating electrical signals as a consequence of such reading, and thereafter comparing the electrical signals with known values to determine authenticity. It has been found with such slot acceptors that it is important to maintain good contact between the paper and the magnetic head during the reading operation in order to obtain desired resolution. In the prior art, spring-loaded wheels, either stationary or retractable, have been provided for urging the bill or currency against the reading head. However, with such structures it has been difficult to obtain proper registration since the magnetic reading head is typically arcuate such that the spring-loaded wheels make only point or tangential contact, often resulting in poor readings.
The prior art has also taught the use of a punch to stack currency once it has been authenticated by the slot acceptor. However, the prior art has not included means to sense that the stacking operation has, in fact, been achieved. The prior art has further been devoid of means to restrict or inhibit stringing or unauthorized attempts at removal of the currency from the stack. Yet further, the prior art has been devoid of means to restrict or inhibit bulging of the bills in the stack.
In the prior art it has not been known to provide a sensor at the top or far end of the note path to assure that the bill has, in fact, reached such end. The result is that the bills may crumple within the path, resulting in a degree of inconsistency and uncontrollability within the stack of bills, as well as limiting the number of bills which might be received in the stack.
It is further known that the prior art generally teaches the use of a drive belt to move the notes along the note path and along vertical rails on either side thereof. The rails have typically been provided with wheels which rotate about a fixed axis perpendicular to the path of note travel. Accordingly, when the bill is punched into the stack, the bill is drug across the wheel orthogonal to the customary plane of rotation, often resulting in a torn bill or one which does not completely release itself from the note path. In somewhat similar manner, the prior art has also taught the movement of bills between a driven belt and an idler belt to a punch position. Here again, the bill or note is punched from frictional engagement between the two belts, often resulting in tears, crumpling, or less than total release of the bill from the note path.
In the prior art, the punch has typically comprised a metal plate having a low coefficient of friction. With such a punch, the bill would typically slide laterally on the punch such that one edge of the bill would free itself from the rail before the other, resulting in failure of the bill to be properly stacked. Indeed, it was found that one edge of the bill often never cleared the rail. Further, it was found that bills characterized by a roll or fold had a tendency to wrap around the punch plate and thereby follow the plate on its return cycle such that the bill was never deposited in the stack.
In light of the foregoing, there is a need in the art for a currency validator of the vertical slot type which overcomes the shortcomings earlier presented.